1. Field of the Invention
The present invention relates to a heat-treating apparatus and a heat-treating method, in which the influence given by the outer air is suppressed in taking out the heated target object to be processed from the process chamber.
2. Description of the Related Art
In general, in the manufacturing process of a semiconductor device, a circuit pattern is transferred in a reduced fashion onto a photoresist layer formed on the surface of a target object to be processed, e.g., a semiconductor wafer, by using the photolithography technology, followed by developing the transferred circuit pattern.
In the photolithography step, the surface of the unprocessed wafer is cleaned first so as to remove the dust and stains from the surface of the wafer, followed by applying a heating-drying treatment to the cleaned wafer. Then, immediately after the cooling, the dried wafer is transferred into a resist coating device so as to form a resist film by, for example, a spin coating method on the surface of the wafer.
Then, the wafer is transferred into a heat-treating apparatus, and pre-baked at a prescribed temperature (about 80° C.) for a prescribed time in order to evaporate the solvent from the resist film. Further, the wafer is cooled to, for example, room temperature (23° C.) and, then, transferred into a light-exposure apparatus for application of the light-exposure.
The wafer after the light-exposure is transferred into a heat-treating apparatus for application of a baking (baking before the development) at a prescribed temperature for a prescribed time. The wafer after completion of the baking is transferred into a developing apparatus for application of a developing and, then, transferred again into the heat-treating apparatus for application of a post-baking (baking after the development) at a prescribed temperature (50 to 180° C.) for a prescribed time so as to evaporate under heating the developing solution or the like remaining on the photoresist layer after the development. Still further, the wafer is transferred into a cooling apparatus for cooling the wafer to room temperature (23° C.), i.e., for controlling the temperature, and, then, transferred into the next process step.
As described above, the wafer after a light-exposure is transferred into a heat-treating apparatus for application of a baking (baking before the development) at a prescribed temperature for a prescribed time. When it comes to a chemical amplification type resist utilizing the heat treatment, the amplification reaction proceeds nonuniformly on the surface of the wafer if the in-plane temperature of the wafer is rendered nonuniform so as to give rise to the problem that adverse effects are given to, for example, the line width forming a pattern. Likewise, if the cooling after the heating is not performed promptly, the amplification reaction proceeds so as to give rise to the problem that adverse effects are given to, for example, the line width forming a pattern on the surface of the wafer. Further, if the time to the cooling after the baking fails to be constant, an additional problem is generated that the line width is varied for each wafer.
As described above, it is important to pay careful attentions to the heat-treating processes performed both before and after the resist coating step and both before and after the developing step. It follows that it is necessary to supervise strictly the thermal history of the wafer.